/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.runtime.io;

import org.apache.flink.api.connector.source.ExternallyInducedSourceReader;
import org.apache.flink.core.io.InputStatus;
import org.apache.flink.streaming.api.operators.SourceOperator;

import java.util.function.Consumer;

/**
 * A subclass of {@link StreamTaskSourceInput} for {@link ExternallyInducedSourceReader}.
 */
public class StreamTaskExternallyInducedSourceInput<T> extends StreamTaskSourceInput<T> {
	private final Consumer<Long> checkpointTriggeringHook;
	private final ExternallyInducedSourceReader<T, ?> sourceReader;

	@SuppressWarnings("unchecked")
	public StreamTaskExternallyInducedSourceInput(
			SourceOperator<T, ?> operator,
			Consumer<Long> checkpointTriggeringHook,
			int inputGateIndex,
			int inputIndex) {
		super(operator, inputGateIndex, inputIndex);
		this.checkpointTriggeringHook = checkpointTriggeringHook;
		this.sourceReader = (ExternallyInducedSourceReader<T, ?>) operator.getSourceReader();
	}

	@Override
	public InputStatus emitNext(DataOutput<T> output) throws Exception {
		InputStatus status = super.emitNext(output);
		if (status == InputStatus.NOTHING_AVAILABLE) {
			sourceReader.shouldTriggerCheckpoint().ifPresent(checkpointTriggeringHook);
		}
		return status;
	}
}
